Sensor integration in lateral flow immunoassays and its applications

ABSTRACT

Lateral flow immunoassay devices for determining the concentration of an analyte in a sample and methods for measuring analyte concentration in sample using such lateral flow immunoassay devices.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional application of U.S. patentapplication Ser. No. 13/658,614, filed on Oct. 23, 2012, the content ofwhich is hereby incorporated by reference herein in its entirety.

FIELD OF INVENTION

The invention relates to a device for Lateral Flow Immunoassays (LFAI's)as a biosensor, methods of improving such LFAI device, and using suchLFAI device in a diagnostic method.

BACKGROUND INFORMATION

Recently there has been an increased interest in predictive,preventative, and particularly personalized medicine which requiresdiagnostic tests with higher fidelity, e.g., sensitivity andspecificity. Lateral Flow Immunoassay (LFIA) devices incorporate suchdiagnostic test and is a well-established technology in Point-of-Care(POC) diagnostics. Low cost, relative ease of manufacture, long shelflife, and ease of use by the customer are some of the advantages thatmake LFIA's very attractive.

The basic principal of a Lateral Flow Immunoassay is shown in FIG. 1.During the early development of LFIA diagnostic devices, the main focuswas primarily on qualitative systems which provide an easy yes or noanswer. The best know qualitative lateral flow system is the pregnancytest.

Currently however, there is an increasing demand for more sensitive,quantitative and also multiplexing measurements which require theimplementation of reader systems. As such, Lateral Flow ImmunoassayDevices can be used in new markets and for new applications.

The capillary flow rate is very important for LFIA's because theeffective concentration of an analyte in a sample decreases with thesquare of an increase in flow rate. For quantitative measurements ofanalytes this relationship is very important because the signalintensity directly correlates with the effective concentration. Thus,the flow speed of the sample across the analytical test line affectsquantitative measurements for the analyte of interest. For example asample viscosity change of 30%, within normal blood viscosity variation,will result in up to 70% signal variation.

The viscosity of different samples, for example blood samples, may varysignificantly. The significant variation in viscosity of samples (andtherefore the capillary flow rate) does not generally affect theperformance of pregnancy tests; however, when a biomarker value, such asits concentration, is to be tested and compared to its previous valuesquantification of the analyte/biomarker is very important.

In LFIA's the flow of the sample through the membrane is driven bycapillary forces. The pore size of the absorbent materials/membranes andthe viscosity of the sample are two parameters that have a directinfluence on the flow speed of the sample through the system. Withrespect to the flow speed/rate damage to the membrane of the LFIA duringthe manufacturing process will introduce multiple artifacts thatadversely affect the flow behavior. For example, separation of themembrane from the backing (or adhesive tape) results in an unobstructedpath for the sample to flow rapidly down the edge of the membrane. Thiswill lead to a concave flow and artifacts in the measurement.

Printed electronics includes certain printing methods which allow thecreation of circuits on a huge variety of substrates such as paper ortextiles. Advantages of printed electronics are that they allowlow-cost, high-volume, high-throughput production of electrical systems.Especially for small, inexpensive and disposable devices this technologycan be very advantageous in improving reliability of quantitativediagnostic test using LFIA's. This makes printed electronics veryattractive to the field of single use biosensors.

Jolke Perelaer et al., “Inkjet-printed silver tracks: low temperaturecuring and thermal stability investigation”, Journal of MaterialsChemistry (2008), vol. 18, pp 3209-3215, describe inkjet printing of inkat low temperature. The possibility to print low temperature curingmaterials increases the amount of usable material on which theelectrodes can be printed (for example printing on temperature sensitivenitrocellulose membranes). Other printing methods such as roll to rollprinting and stamping are also possible.

Some other key factors that affect the signal produced in a lateral flowtest include temperature and ionic strength (including pH) of thesolution. Including sensors and actuators that measure and influencesuch conditions is also important in reducing variations in the signalgenerated.

SUMMARY OF INVENTION

A lateral flow immunoassay device comprising at least one electricalsensor can measure one or more parameters which affect the signalintensity of an analyte of interest in a sample. An integrated printedelectrical sensor in a lateral flow immunoassay device can measure suchparameters which include for example the flow rate, flow shape,temperature or ionic concentration of the sample when flowing across thedevice.

In one embodiment there is provided a lateral flow immunoassay devicefor measuring an analyte having a solid support including absorbentmaterial for providing capillary flow comprising:

a) a sample portion for receiving a sample;

b) a conjugate portion comprising conjugate particulate material;

b) a diagnostic portion comprising a binder for the analyte;

c) an absorbent portion of absorbent material for providing capillaryflow; and

d) at least one electrical sensor,

wherein the sample portion, conjugate portion, diagnostic portion, andabsorbent portion are in capillary flow communication, whereby thesample flows across the binder in the diagnostic portion to providecontact between the sample and the binder.

The at least one electrical sensor in the lateral flow immunoassaydevice is connected to a processing unit for computing one or moreparameters relating to the sample. The parameter(s) that are computedare those that affect the intensity of the signal from the boundlabeled-analyte complex, thereby affecting the computation of theconcentration of the analyte in the sample. For example such parametersof the sample include the flow rate of the sample across the diagnosticportion, the flow shape of the sample across the diagnostic portion, thetemperature of the sample at the diagnostic portion, the pH of thesample at the diagnostic portion, and the ionic concentration of thesample at the diagnostic portion.

In another embodiment there is provided a method of determining theconcentration of an analyte in a sample comprising determining theanalyte in the sample and a parameter of the sample in a lateral flowimmunoassay device, wherein the lateral immunoassay device comprises asolid support including absorbent material for providing capillary flowcomprising:

a) a sample portion for receiving a sample;

b) a conjugate portion comprising conjugate particulate material;

b) a diagnostic portion comprising a binder for the analyte;

c) an absorbent portion of absorbent material for providing capillaryflow; and

d) at least one electrical sensor,

wherein the sample portion, conjugate portion, diagnostic portion, andabsorbent portion are in capillary flow communication, whereby thesample flows across the binder in the diagnostic portion to providecontact between the sample and the binder.

The concentration of the analyte in the sample is computed bydetermining the signal intensity of the labeled-analyte bound to thediagnostic portion of the lateral flow immunoassay device and taking inconsideration one or more of the parameters that were determined for thesample flowing across the diagnostic portion of the lateral flowimmunoassay device.

BRIEF DESCRIPTION OF FIGURES

FIG. 1: A schematic representation of a lateral flow immunoassay device.

FIG. 2: A schematic representation of a setup for a flow speedmeasurement in a lateral flow immunoassay device.

FIG. 3: A schematic representation of electrode pairs for flow shapesensors to determine non-uniform flow shape.

FIG. 4A: Showing measurements of a simple lateral flow immunoassaydevice for measuring the flow shape of a sample: non-uniform flow shapeelectrode (U2) is short-circuited prior to when flow shape electrode(U3) is short-circuited.

FIG. 4B: Showing measurements of a simple lateral flow immunoassaydevice for measuring the flow shape of a sample: graph showing themeasured current signal (with after-pulse removal).

FIG. 5A: Graph showing measurements of different flow speeds due todifferent amounts of sample volume: 500 μl of PBS (flow front moves veryslowly).

FIG. 5B: Graph showing measurements of different flow speeds due todifferent amounts of sample volume: 1000 μl of PBS (membrane isflooded).

FIG. 6: Graph showing temperature sensing. Temperature sweep started at30° C. to 100° C. on a hotplate.

FIG. 7A: Schematic representation of alternative electrical sensorintegration on a solid support of a later flow immunoassay device: a)the electrical sensor is on a portion of the solid support differentfrom the diagnostic portion.

FIG. 7B: Schematic representation of alternative electrical sensorintegration on a solid support of a later flow immunoassay device:electrical sensor integration is below the membrane of the diagnosticportion through a support layer/membrane.

FIG. 7C: Schematic representation of alternative electrical sensorintegration on a solid support of a later flow immunoassay device:electrical sensor integration is through gaps in the membrane of thediagnostic portion of the solid support.

FIG. 8: Schematic representation of an integration of printed sensors ina lateral flow device. The intensity of the test line is adjusted by thedata from the flow speed measurement which can be carried out by forexample a CMOS sensor which transmits the signal to a display.

DETAILED DESCRIPTION

Electrical sensors can be integrated into Lateral Flow Immunoassay(LFIA) devices for determining parameters of a sample, which parametersaffect the accuracy for measuring the concentration of an analyte ofinterest in such sample. Different kinds of printed electrical sensorsthat can be integrated into a Lateral Flow Immunoassay (flow speedsensor, flow shape sensor, temperature sensor) are provided. Nearlyevery printing process can be used to print these conductive electrodesfor example screen-printing, gravure printing or inkjet-printing butalso spraying or brushing techniques. The materials for these electricalsensors include for example silver, platinum, carbon, copper or goldinks or pastes.

Since some of the solvents of conductive materials can attack themembranes (especially nitrocellulose) used in the diagnostic portions ofthe LFIA, the electrodes can also be applied on different parts of thesystem (for e.g. bellow the nitrocellulose membrane on thebacking-access through the backing). For example certain alternativesfor integrating a printed electrode sensor in a LFIA device are shown inFIG. 7. These include printing of the electrode on a backing or supportmaterial below the membrane, wherein the electrode may be accessedthrough the backing or solid support material. As is shown for examplein FIG. 7b wherein the electrodes could easily be connected through thebacking. Alternatively, the electrodes are printed on the diagnosticportion (the diagnostic membrane) or in gaps of such diagnostic portionof the LFIA device. In another alternative, the electrodes are notprinted electrodes but comprise non-printed electrodes applies to orthrough one or more of the various portions of the LFIA device.

As such there is provided a lateral flow immunoassay device formeasuring an analyte having a solid support including absorbent materialfor providing capillary flow comprising:

a) a sample portion for receiving a sample;

b) a conjugate portion comprising conjugate particulate material;

b) a diagnostic portion comprising a binder for the analyte;

c) an absorbent portion of absorbent material for providing capillaryflow; and

d) at least one electrical sensor,

wherein the sample portion, conjugate portion, diagnostic portion, andabsorbent portion are in capillary flow communication, whereby thesample flows across the binder in the diagnostic portion to providecontact between the sample and the binder. Binding of the analyte in thesample (and the conjugate) to the binder, located on a test-line of thediagnostic portion, will result in a signal being generated at thatlocation. The intensity of the signal being generated is an indicationof the concentration of the analyte of interest in the sample applied tothe sample portion of the device.

In such a device the sample portion, conjugate portion, diagnosticportion, and absorbent portion can be placed on a single solid supportor backing material. This solid support or backing material may beflexible but is inert and provides sufficient support to maintain acapillary flow of the sample through the various portions that are ofabsorbent material.

The diagnostic portion of the lateral flow immunoassary device may beprepared using a membrane. Such diagnostic membrane can for example beselected from a nitrocellulose membrane, a polyvinylidene fluoridemembrane, a nylon membrane that is optionally charge modified, and apolyethersulfone membrane. The diagnostic membrane further comprises animmobilized binder for the analyte. Such binder can be any molecule orbio-molecule with which the analyte of interacts so as to result in abinder-analyte complex that is immobilized onto the diagnostic membrane.Examples of such binders may be an antibody, antigen, protein, enzyme orpart thereof, substrate or part thereof, peptide, DNA, or RNA.

An electrical sensor integrated in such LFIA device is preferably aprinted electrical sensor. The electrical sensor can have one or moreelectrode pairs that are printed on the solid support of the LFIAdevice. Printing of the electrode pairs can be on any one of the sampleportion, diagnostic portion, and/or absorbent portion of the solidsupport. Preferably, the electrodes are printed on the diagnosticportion of the device which contains the binder material for interactionwith the analyte. Alternatively, the applied electrodes are non-printedelectrodes.

The electrical sensor can be connected to a processing unit forcomputing one or more parameters of the sample. Such processing unit cancomprise for example a CMOS unit for processing the data obtained,determining the value of the parameter of interest of the sample andcomputing the concentration of the analyte detected on the diagnosticportion/membrane of the LFIA device. Such parameter of the sample canfor example be the flow rate of the sample across the diagnosticportion, the flow shape of the sample across the diagnostic portion, thetemperature of the sample at the diagnostic portion, the pH of thesample at the diagnostic portion, and/or the ionic concentration of thesample at the diagnostic portion.

In addition, the processing unit preferably comprises a display to, forexample, display the concentration of the analyte in the sample or anyother measured or computed value of interest thereof. Further, theprocessing unit may be integrated in the LFIA device or the processingunit is connected to the LFAI device externally.

In one embodiment the LFAI device is provided with a flow speed sensorwhich comprises at least one, preferably at least two, electrode pairswhich are integrated on the diagnostic part of the Lateral Flow Device.In one such embodiment two electrodes pairs are used, wherein oneelectrode pair is located in the flow direction before the test line onthe diagnostic portion and the second pair of electrodes is located inthe flow direction after the test lines of the diagnostic portion. Aresistance measurement between corresponding electrodes providesinformation about the flow speed of the sample. When the sample crossesan electrode pair the resistance will drop due to the higherconductivity of the sample (fluid) compared to the conductivity of thedry test strip or diagnostic membrane. FIG. 8 shows an example of howsuch sensor system is included into a Lateral Flow Immunoassay device.For example the information from the color or fluorescence measurementcan be adjusted by the information obtained from the flow speedmeasurement. The adjustment can for example be done by a CMOS-Sensor.

This combination of the label/signal readout for the analyte and flowrate of the sample compensates for example the effect of viscositychange.

In another embodiment the LFIA device is provided with a flow shapesensor. The flow shape sensor comprises electrode pairs that areintegrated on the diagnostic part of the Lateral Flow Immunoassay deviceas shown for example in FIG. 3. Multiple electrode pairs are appliedside-by-side to each other in an array perpendicular to the flowdirection of the sample across the LFIA device. Depending on the desiredresolution any amount of electrodes can be integrated on the diagnosticportion/membrane. The only limitation is the width of the diagnosticportion/membrane and the width of the electrode. When the flow shape isnon-uniform several electrodes will get short-circuited earlier thanothers. For example, where there is a convex flow shape occurring on thediagnostic membrane the electrodes in the middle of the diagnosticportion/membrane will get short-circuited earlier than outsideelectrodes. These changes in the current signal can be measured. Fromcompiling the data from the multiple electrode pairs the geometry of theflow shape can be determined, which then can be used to obtain importantinformation about the signal intensity along the reaction lines.

In addition, a change in the temperature of a solution is correlatedwith the flow speed. Thus, in yet another embodiment the LFIA device isprovided with a temperature sensor. A temperature sensor can getintegrated on any membrane of the lateral flow device. By applying adefined structure of conductive material resistances in a defined rangea temperature sensor can be integrated on the device. With changingtemperature also the resistance of the (printed) electronic temperaturesensor will change in a defined way

Furthermore, in an embodiment having at least one, preferably at leasttwo, temperature sensors and a heating element the flow rate can also bemeasured when the device is already wet such as in a device withcontinuous flow. As described herein a difference in the resistance inan electronic, here temperature, sensor provides a measurement of theflow time of the sample over the LFIA device from which the flow ratecan be obtained. In such an embodiment, in a device with for examplecontinuous flow, a heating element that is located before, in the flowdirection, of the test line or diagnostic portion increases thetemperature of the (sample) fluid. This can be measured by a temperaturesensor. The flow of the (sample) fluid of increased temperature acrossthe LFIA device, over a pre-determined distance, results in a differencethat can be measured with such a temperature sensor. Form the determinedflow time the flow speed/rate can be obtained. Similarly a combinationof an array of such temperature sensors can be used to measure flowshape in such a device that is already wet. In such embodiment the LFIAdevice having at least one temperature sensor and a heating elementcomprises an array of temperature sensors located perpendicular to theflow direction in the LFIA device. As described, a change in theresistance measured by one of the temperature sensor of such an array ofsensors provides a measurement of the flow time in one area defined bythat one temperature sensor. The combination of the various flow timesfrom the array of sensors provides a measurement of the flow shape ofthe sample across the LFIA device.

For any of the embodiments described a processing unit translates thevalues obtained from the electron pairs in the electrical sensors to ameasured value of a parameter of the sample. After-pulse removal can beused in case to remove signal changes that may occur. Especially whenthere is very low sample volume available, the current signal willincrease much slower to its maximum value than when there is a highamount of sample volume available (see FIG. 5). In a capillary flowdevice as a Lateral Flow Immunoassay device, the flow speed/rate of thesample across the diagnostic portion, comprising the binder for theanalyte in a test line, is inversely related to the capillary flow time.The printed electrical sensors can determine the capillary flow time,the time needed to for the sample to travel a defined length through theabsorbent material of the diagnostic portion. This capillary flow timeis inversely related to the flow speed/rate of the sample across theLFIA device.

Further the effective concentration of an analyte in a sample isinversely related to the square of the change in flow rate. Accordingly,in adjusting for the flow speed/rate of the sample in determining theconcentration of the analyte in a sample, a calibration algorithm may beused for accessing a look up table, which calibration is pre-determinedbased on the (absorbent) materials used for manufacturing the LFIAdevice and for a standard solution of a sample to be tested using suchLFIA device.

The sensors and the actuators for the LFIA devices according to any ofthe embodiments can be prepared using printed electronics (e.g.,conductive inks and temperature sensitive materials). As discussed theycan be printed either directly on (for example) the nitrocellulose, onthe backing material, or on a top layer that is attached to the device.Likewise, in an alternative embodiment, non-printed electrodes may beapplied either directly onto the absorbent material (such as thenitrocellulose membrane), or through the backing material of the device.The interface to the electronic integrated circuits can be made by useof flex circuits or similar technologies.

In another embodiment there is provided a method of determining theconcentration of an analyte in a sample comprising determining theanalyte in the sample and a parameter of the sample in a lateral flowimmunoassay device, wherein the lateral immunoassay device comprises asolid support including absorbent material for providing capillary flowcomprising:

a) a sample portion for receiving a sample;

b) a conjugate portion comprising conjugate particulate material;

b) a diagnostic portion comprising a binder for the analyte;

c) an absorbent portion of absorbent material for providing capillaryflow; and

d) at least one electrical sensor,

wherein the sample portion, conjugate portion, diagnostic portion, andabsorbent portion are in capillary flow communication, whereby thesample flows across the binder in the diagnostic portion to providecontact between the sample and the binder.

In FIG. 1 a solid support (1) comprising a sample portion (2), aconjugate portion (3), a diagnostic portion (4) and an absorbent portion(also referred to as a wick) (5) are shown. A sample (10) is applied tothe sample portion (2) of the lateral flow immunoassay (LFIA) device.The sample flows by way of capillary flow towards the absorbent material(5) of the device. When passing through the conjugate portion (3) alabel of particulate conjugate material interacts with the analyteforming a complex. Such complex continues to flow through capillaryaction across the diagnostic portion (4) of the LFIA device. A binder ona test line (6) interacts with the analyte of interest in the sample andimmobilizes the analyte and conjugate particulate matter on the testline (6), the intensity of this label (conjugate particulate matter) ismeasured to determine the concentration of the analyte present in thesample.

Electrical sensors with electrode pairs (U1 and U2) located on the solidsupport or parts thereof, such as the diagnostic portion (4) of the LFIAdevice, as in FIG. 2 can be used to determine a parameter of the samplesuch as the flow speed/rate of the sample across the diagnostic portion(4) of the LFIA device. The flow speed can be computed using aprocessing unit (20), which may consist of various components so as forexample a printed control board (21), a data acquisition board (22), anda computer program (23). In FIG. 3, an array of multiple of suchelectrical sensors with electrode pairs (U2, U3, U4, U5, U7, U8, and U9)together with electrode pair (U1) are printed on a diagnostic portion(4) of the LFIA device for determining the flow shape of a sample acrossthe diagnostic portion (4). Likewise the array of electrode pairs (U2and U3) together with electrode pair (U3) in FIG. 4a is used todetermine the flow shape of the sample across diagnostic portion (4).

In FIG. 7 printed electrode pairs (U1 and U2) can be integrated onportions of the solid support that is different than the diagnosticportion (4), such as in 7 a where the electrode pair (U1) is printedonto the sample portion (2) and electrode pair (U2) is printed onto theabsorbent portion (5). In the alternative, in FIG. 7b electrode pairs(U1 and U2) are printed on the backing or support (1) which is coveredwith the nitrocellulose membrane of the diagnostic portion (4).Electrode pairs (U1 and U2) can be accessed through the backing/support(1). In FIG. 7c another alternative is shown wherein the printedelectrode pairs (U1 and U2) are printed in gaps in the nitrocellulosemembrane of the diagnostic portion (4). Other variations of these mayalso be possible.

Integration of printed sensors in a lateral flow immunoassay device canbe as in FIG. 8. Electrode pairs (U1 and U2) are printed on thediagnostic portion (4) of the lateral flow immunoassay device. Thesignal intensity from test line (6) such as color intensity orfluorescence intensity is measured and computed together with themeasured values from electrode pairs (U1 and U2) by a processing unit(20) which can comprise a CMOS-sensor (30) and an integrated or externaldisplay (40).

EXAMPLES

Lateral Flow Immunoassay were prepared using the following materials.The diagnostic membrane (Hiflow Plus HFB 13504), a conjugate pad (G041glass fiber conjugate pad) and the absorbent pad (C083 celluloseAbsorbent) were all from Millipore. The sample pad (CF5) was fromWhatman. Preparation of the conjugate pad was done using the protocol byS. Wang et al. “Development of a colloidal gold-based lateral flowimmunoassay for the rapid simultaneous detection of zearalenone anddeoxynivalenol”, Anal. Bioanal. Chemistry (2007). The protocol to treatthe nitrocellulose diagnostic membrane was described in “Lateral FlowTests” Technote, Bangs Laboratories. Inc. (2008).

Example 1 (Flow Speed Sensor)

Conductive silver ink (DuPont 4929N) was applied to the treatednitrocellulose membrane using an art brush. The electrodes wereconnected to a printed circuit board (PCB) (see FIG. 2). A fixed voltageof v=1V was applied between each electrode pair and the correspondingcurrent was measured by an instrumentation amplifier on the PCB. A DataAcquisition Board from National Instruments was used as the interfacebetween the PCB and the computer (Matlab-Mathworks).

Two different solutions with different viscosities (PBS and Glyceroldiluted in PBS 1:3) were applied to the sample pad of the LFIA. Asolution of 1:3 PBS Glycerol decreases the flow speed to around ¼ of theflow speed measured with pure PBS solution.

To show the influence of wrong sample application on the flow speed avery low sample volume (500 μl) and a high sample volume (1000 μl) werecompared with each other. The flow front of the low volume sample movedvery slowly along the diagnostic membrane (v≈3 cm/min) where the flowfront of the high volume sample moved very fast (v≈1 cm/min) and evenflooded the membrane. FIG. 5 shows the results of the flow speedmeasurement.

Example 2 (Flow Shape Sensor)

Conductive silver ink (DuPont 4292N) was applied to the treatednitrocellulose membrane using an art brush. The setup that was used isshown in FIG. 4a wherein multiple electrode pairs were applied to thetreated nitrocellulose membrane. A non-uniform flow shape was created onpurpose by applying a much larger amount of sample volume on the leftside of the sample pad. The flow shape that was created looked similarto the one indicated in FIG. 4a . The results (after pulse removal) areshown in FIG. 4b . Due to the non-uniform flow front electrode 2 gotshorted prior to electrode 3 being shorted.

Example 3 (Temperature Sensor)

Conductive platinum ink (DuPont BQ321) was printed on the sample pad ofthe LFIA. The resistance was set to 110Ω at room temperature. Thetemperature of a hotplate was slowly increased to 100° C. An increase ofthe resistance was observed that was similar to a standard platinumPt100 temperature sensor.

1. A method comprising: determining a parameter of a sample in a lateralflow immunoassay device, wherein: the lateral immunoassay devicecomprises: a) a solid support; b) a sample portion for receiving thesample; c) a conjugate portion comprising conjugate particulatematerial; d) a diagnostic portion comprising a binder for an analyte inthe sample; e) an absorbent portion of absorbent material for providingcapillary flow; and f) at least one electrical sensor; and the sampleportion, conjugate portion, diagnostic portion, and absorbent portionare in capillary flow communication, whereby the sample flows across thebinder in the diagnostic portion to provide contact between the sampleand the binder; and determining a concentration of the analyte in thesample based on the determined parameter.
 2. The method of claim 1,wherein the at least one electrical sensor is connected to a processingunit comprising a display.
 3. The method of claim 1, wherein theparameter includes at least one of a flow rate of the sample across thediagnostic portion, a flow shape of the sample across the diagnosticportion, a temperature of the sample at the diagnostic portion, a pH ofthe sample at the diagnostic portion, and an ionic concentration of thesample at the diagnostic portion.
 4. The method of claim 1, wherein: thesample: flows through the conjugate portion, whereby the analyte bindsto and forms a complex with the conjugate particulate material; andflows through the diagnostic portion, whereby the binder interacts withthe analyte and immobilizes the analyte and conjugate particulatematerial complex; the conjugate particulate material bound to theanalyte generates a signal; the method further comprises measuring asignal intensity from the conjugate particulate material bound to theanalyte at the diagnostic portion; the determining of the parameterincludes measuring the parameter at the diagnostic portion; and thedetermination of the concentration of the analyte is further based onthe measured signal intensity.
 5. The method of claim 4, wherein theparameter of the sample affects the signal intensity from the boundanalyte-conjugate particular material complex.
 6. The method of claim 5,wherein the parameter is the flow rate of the sample across thediagnostic portion, the flow shape of the sample across the diagnosticportion, the temperature of the sample at the diagnostic portion, the pHof the sample at the diagnostic portion, and/or the ionic concentrationof the sample at the diagnostic portion.
 7. The method of claim 4,wherein the at least one electrical sensor is connected to a processingunit configured to measure the signal intensity, measure the parameterof the sample, and determine the concentration of the analyte.
 8. Themethod of claim 7, wherein the processing unit is also connected to adisplay and is configured to display the determined analyteconcentration on the display.
 9. The method of claim 7, wherein theprocessing unit is connected to the lateral flow immunoassay deviceexternally.
 10. The method of claim 7, wherein the processing unit isintegrated into the lateral flow immunoassay device.
 11. The method ofclaim 1, wherein the at least one electrical sensor and the binder forthe analyte are both placed on one side of the solid support, the atleast one electrical sensor being located on a portion of the solidsupport different from the binder for the analyte.
 12. The method ofclaim 1, wherein the at least one electrical sensor is positioneddownstream of the binder in a capillary flow direction.
 13. The methodof claim 1, wherein the at least one electrical sensor is printed orapplied directly on the diagnostic portion.
 14. The method of claim 13,wherein the at least one electrical sensor comprises at least oneelectrode pair.
 15. The method of claim 13, wherein the at least oneelectrical sensor comprises two electrode pairs to determine a flow rateof the sample across the diagnostic portion.
 16. The method of claim 15,wherein, when determining the concentration of the analyte, acalibration algorithm is used to access a look up table.
 17. The methodof claim 13, wherein the at least one electrical sensor comprises aseries of multiple electrode pairs arranged side-by-side across the flowpath of the sample to determine a flow shape of the sample across thediagnostic portion.
 18. The method of claim 13, wherein the at least oneelectrical sensor comprises a defined structure of conductive materialresistances in a define range for determining a temperature of thesample flowing across the diagnostic portion.
 19. The method of claim13, wherein the at least one electrical sensor comprises at least onetemperature sensor, and the device further comprises a heating elementlocated, in the flow direction of the sample, before the at least onetemperature sensor.
 20. The method of claim 13, wherein the at least oneelectrical sensor comprises a series of multiple temperature sensorsarranged side-by-side across the flow path of the sample, and the devicefurther comprises a heating element located, in the flow direction ofthe sample, before the at least one temperature sensor, to determine aflow shape of the sample across the diagnostic portion of the lateralflow device.